36 Internal probes

In order to aid in debugging and monitoring internal behavior,
the GNU C Library exposes nearly-zero-overhead SystemTap probes marked with
the libc provider.

These probes are not part of the GNU C Library stable ABI, and they are
subject to change or removal across releases. Our only promise with
regard to them is that, if we find a need to remove or modify the
arguments of a probe, the modified probe will have a different name, so
that program monitors relying on the old probe will not get unexpected
arguments.